Labels

ABSTRACT

Herein is described a method of providing a printed label. The method comprises: providing a printed label substrate having disposed thereon an electrostatically printed ink; applying a UV curable overcoat composition to the printed ink, wherein the UV curable overcoat composition comprises (i) a component selected from UV curable monomers and UV curable oligomers, and (ii) a slip agent; curing the overcoat composition under UV irradiation with an output power of 2500 W or less. Printed labels and an ink and overcoat composition set are also described herein.

BACKGROUND

Printed labels are used on or in many types of product to displayinformation, differentiate products and comply with regulatoryrequirements, such as ingredients lists, safety warnings, and so forth.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows schematically an example of a method for providing aprinted label.

FIG. 2 shows schematically another example of a method of providing aprinted label.

FIG. 3 shows schematically a further example of a method of providing aprinted label.

DETAILED DESCRIPTION

Before the present disclosure is disclosed and described, it is to beunderstood that this disclosure is not restricted to the particularprocess features and materials disclosed herein because such processfeatures and materials may vary somewhat. It is also to be understoodthat the terminology used herein is used for the purpose of describingparticular examples.

It is noted that, as used in this specification and the appended claims,the singular forms “a”, “an”, and “the” include plural referents unlessthe context clearly dictates otherwise.

As used herein, “carrier fluid”, “carrier liquid”, or “carrier vehicle”,in the context of electrostatic ink compositions, refers to the fluid inwhich pigment particles, colorant, charge directors and other additivescan be dispersed to form a liquid electrostatic composition orelectrophotographic composition. The carrier liquids may include amixture of a variety of different agents, such as surfactants,co-solvents, viscosity modifiers, and/or other possible ingredients.

As used herein, “electrostatic ink composition”, “liquidelectrophotographic composition” or “liquid electrostatic inkcomposition” generally refers to an ink composition that is generallysuitable for use in an electrostatic printing process, sometimes termedan electrophotographic printing process. It may comprise pigmentparticles, which may comprise a thermoplastic resin.

As used herein, “pigment” generally includes pigment colorants, magneticparticles, aluminas, silicas, and/or other ceramics or organometallics,whether or not such particulates impart colour. Thus, though the presentdescription primarily exemplifies the use of pigment colorants, the term“pigment” can be used more generally to describe not just pigmentcolorants, but other pigments such as organometallics, ferrites,ceramics, and so forth.

As used herein, “co-polymer” refers to a polymer that is polymerizedfrom at least two monomers.

As used herein, “melt flow rate” generally refers to the extrusion rateof a resin through an orifice of defined dimensions at a specifiedtemperature and load, usually reported as temperature/load, for example,190° C./2.16 kg. Flow rates can be used to differentiate grades orprovide a measure of degradation of a material as a result of molding.In the present disclosure, “melt flow rate” is measured per ASTMD1238-04c Standard Test Method for Melt Flow Rates of Thermoplastics byExtrusion Plastometer. If a melt flow rate of a particular polymer isspecified, unless otherwise stated, it is the melt flow rate for thatpolymer alone, in the absence of any of the other components of theelectrostatic composition.

As used herein, “acidity”, “acid number”, or “acid value” refers to themass of potassium hydroxide (KOH) in milligrams that neutralizes onegram of a substance. The acidity of a polymer can be measured accordingto standard techniques, for example, as described in ASTM D1386. If theacidity of a particular polymer is specified, unless otherwise stated,it is the acidity for that polymer alone, in the absence of any of theother components of the liquid toner composition.

As used herein, “melt viscosity” generally refers to the ratio of shearstress to shear rate at a given shear stress or shear rate. Testing isgenerally performed using a capillary rheometer. A plastic charge isheated in the rheometer barrel and is forced through a die with aplunger. The plunger is pushed either by a constant force or at constantrate depending on the equipment. Measurements are taken once the systemhas reached steady-state operation. One method used is measuringBrookfield viscosity @ 140° C., units are mPa·s or cPoise. In someexamples, the melt viscosity can be measured using a rheometer, e.g., acommercially available AR-2000 Rheometer from Thermal AnalysisInstruments, using the geometry of 25 mm steel plate-standard steelparallel plate, and finding the plate over plate rheometry isotherm at120° C., 0.01 Hz shear rate. If the melt viscosity of a particularpolymer is specified, unless otherwise stated, it is the melt viscosityfor that polymer alone, in the absence of any of the other components ofthe electrostatic ink composition.

A certain monomer may be described herein as constituting a certainweight percentage of a polymer. This indicates that the repeating unitsformed from the said monomer in the polymer constitute said weightpercentage of the polymer.

If a standard test is mentioned herein, unless otherwise stated, theversion of the test to be referred to is the most recent at the time offiling this patent application.

As used herein, “electrostatic printing” or “electrophotographicprinting” generally refers to the process that provides an image that istransferred from a photo imaging substrate either directly or indirectlyvia an intermediate transfer member to a substrate, for example a labelsubstrate. As such, the image is not substantially absorbed into thephoto imaging substrate on which it is applied. Additionally,“electrophotographic printers” or “electrostatic printers” generallyrefer to those printers capable of performing electrophotographicprinting or electrostatic printing, as described above. “Liquidelectrophotographic printing” is a specific type of electrophotographicprinting where a liquid composition is employed in theelectrophotographic process rather than a powder toner. An electrostaticprinting process may involve subjecting the electrostatic composition toan electric field, for example, an electric field having a fieldgradient of 50-400 V/μm, or more, in some examples, 600-900V/μm, ormore.

As used herein, “substituted” may indicate that a hydrogen atom of acompound or moiety is replaced by another atom such as a carbon atom ora heteroatom, which is part of a group referred to as a substituent.Substituents include, for example, alkyl, alkoxy, aryl, aryloxy,alkenyl, alkenoxy, alkynyl, alkynoxy, thioalkyl, thioalkenyl,thioalkynyl, thioaryl, and so forth.

As used herein, “heteroatom” may refer to nitrogen, oxygen, halogens,phosphorus, or sulfur.

As used herein, “alkyl”, or similar expressions such as “alk” in alkoxy,may refer to a branched, unbranched, or cyclic saturated hydrocarbongroup, which may, in some examples, contain from 1 to about 50 carbonatoms, or 1 to about 40 carbon atoms, or 1 to about 30 carbon atoms, or1 to about 10 carbon atoms, or 1 to about 5 carbon atoms.

The term “alkenyl” may refer to a branched, unbranched, or cyclicunsaturated hydrocarbon group, which may include one or more doublebonds, one or more triple bonds or any combination thereof, which may ormay not be conjugated, and, in some examples, are not aromatic. Alkenylgroups described herein may contain, but are not limited to, 2 to about50 carbon atoms, or 2 to about 40 carbon atoms, or 2 to about 30 carbonatoms, or 2 to about 20 carbon atoms, or 2 to about 10 carbon atoms, or2 to about 5 carbon atoms.

The term “aryl” may refer to a group containing a single aromatic ringor multiple aromatic rings that are fused together, directly linked, orindirectly linked (such that the different aromatic rings are bound to acommon group such as a methylene or ethylene moiety). Aryl groupsdescribed herein may contain, but are not limited to, from 5 to about 50carbon atoms, or 5 to about 40 carbon atoms, or 5 to about 30 carbonatoms or more, and may be selected from, phenyl and naphthyl.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be a littleabove or a little below the endpoint to allow for variation in testmethods or apparatus. The degree of flexibility of this term can bedictated by the particular variable as would be understood in the art.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not just the numerical valuesexplicitly recited as the end points of the range, but also to includeall the individual numerical values or sub-ranges encompassed withinthat range as if each numerical value and sub-range is explicitlyrecited. As an illustration, a numerical range of “about 1 wt % to about5 wt %” should be interpreted to include not just the explicitly recitedvalues of about 1 wt % to about 5 wt %, but also to include individualvalues and subranges within the indicated range. Thus, included in thisnumerical range are individual values such as 2, 3.5, and 4 andsub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This sameprinciple applies to ranges reciting a single numerical value.Furthermore, such an interpretation should apply regardless of thebreadth of the range or the characteristics being described.

As used herein, unless the context indicates otherwise, wt % values areto be taken as referring to a weight-for-weight (w/w) percentage ofsolids in the ink composition, and not including the weight of anycarrier fluid present.

Unless otherwise stated, any feature described herein can be combinedwith any aspect or any other feature described herein.

In an aspect, there is provided a method of providing a printed label.The method may comprise:

-   -   providing a printed label substrate having disposed thereon an        electrostatically printed ink;    -   applying a UV curable overcoat composition to the printed ink,        wherein the UV curable overcoat composition comprises        -   (i) a component selected from UV curable monomers and UV            curable oligomers, and        -   (ii) a slip agent;    -   curing the overcoat composition under UV irradiation.

In an aspect there is provided a method of providing a printed label.The method may comprise:

-   -   providing a printed label substrate having disposed thereon an        electrostatically printed ink;    -   applying a UV curable overcoat composition to the printed ink,        wherein the UV curable overcoat composition comprises        -   (i) a component selected from UV curable monomers and UV            curable oligomers, and        -   (ii) a slip agent;    -   curing the overcoat composition under UV irradiation with an        output power of 2500 W or less.

In an aspect there is provided a method of providing a printed label.The method may comprise:

-   -   providing a printed label substrate having disposed thereon an        electrostatically printed ink;    -   applying a UV curable overcoat composition to the printed ink,        wherein the UV curable overcoat composition comprises        -   (i) a component selected from UV curable monomers and UV            curable oligomers, and        -   (ii) a slip agent;    -   curing the overcoat composition under UV irradiation with an        output intensity of 40 mJ/cm² or less.

In another aspect, there is provided a printed label. The printed labelmay comprise:

-   -   a label substrate;    -   an electrostatically printed ink disposed on the substrate; and    -   an overcoat composition disposed on the printed ink that has        been cured under UV irradiation;    -   wherein the overcoat composition comprises        -   (i) a component selected from UV curable monomers and UV            curable oligomers, and        -   (ii) a slip agent.

In a further aspect, there is provided an ink and overcoat set. The inkand overcoat set may comprise:

-   -   a label substrate;    -   an electrostatically printed ink disposed on the substrate; and    -   an overcoat composition disposed on the printed ink that has        been cured under UV irradiation;    -   wherein the overcoat composition comprises        -   (i) a component selected from UV curable monomers and UV            curable oligomers;        -   (ii) a slip agent; and        -   (iii) a photoinitiator.

In light of the importance of much of the information provided on labelsto both consumers and regulatory bodies, it is desirable that printedlabels are sufficiently durable that this information remains visibleunder the conditions that the product is packaged (for example, duringsterilization and/or bottling), stored (whether, for example, in arefrigerated environment or hot and/or humid shelving), transported,displayed and used. This provides a particular challenge for productsthat remain in a wet environment for a prolonged period of time, such asshampoo bottles and beer bottles. The present inventors have found thatmany labels printed with electrostatic printing inks are vulnerable tothe chemical and water environments to which they may be subjectedduring their lifecycle. The present inventors have found that examplesof the methods and products described herein avoid or at least mitigateat least one of these difficulties. They have found that examples of themethod and products have increased durability under chemical and waterenvironments, providing increased scratch and rub resistance to theprinted labels, following exposure to water.

Printed Label

In some examples, a printed label is described. The printed label may beproduced by any of the methods described herein. Each component of theprinted label will be discussed in the sections that follow.

UV Curable Overcoat Composition

The UV curable overcoat composition may be applied to the printed ink.In some examples, the printed label may comprise a printed labelsubstrate and an overcoat composition disposed on the printed ink thathas been cured under irradiation. In some examples, the printed labelmay comprise a label substrate, an electrostatically printed inkdisposed on the label substrate and an overcoat composition disposed onthe printed ink that has been cured under irradiation.

The UV curable overcoat composition may comprise (i) a componentselected from UV curable monomers and UV curable oligomers or mixturesthereof; and (ii) a slip agent.

The UV curable overcoat composition may comprise (i) a componentselected from UV curable monomers and UV curable oligomers or mixturesthereof; (ii) a slip agent and (iii) a photoinitiator.

In some examples, the UV curable overcoat composition may comprise acomponent selected from UV curable monomers and UV curable oligomers ormixtures thereof; a slip agent; a photoinitiator; and an overcoatcomposition solvent In some examples, the overcoat composition solventmay be a carrier liquid as described below. The overcoat compositionsolvent may be a solvent selected from water, an alcohol, for example, aC1 to C3 alkanol, such as methanol or ethanol, esters and glycol ethers.

As used herein, oligomers are short polymers which may contain no morethan 100 monomers. In some examples, oligomers are polymers that have achain length of 100 monomers or less, for example, 50 monomers or less,for example, 40 monomers or less, for example, 30 monomers or less, forexample, 20 monomers or less, for example, 15 monomers or less or, forexample, 10 monomers or less.

In some examples, the overcoat composition is cured under UVirradiation. In some examples, the UV irradiation may be emitted by a UVsource, for example, a UV lamp or a UV bulb.

In some examples, the curing of the overcoat composition under UVirradiation is performed with a UV output power of 2500 W or less, insome examples, 2400 W or less, in some examples, 2300 W or less, in someexamples, 2200 W or less, in some examples, 2100 W or less, in someexamples, 2000 W or less, in some examples, 1900 W or less, in someexamples, 1800 W or less, in some examples, 1700 W or less, in someexamples, 1600 W or less, in some examples, 1500 W or less, in someexamples, 1400 W or less, in some examples, 1300 W or less, in someexamples, 1200 W or less, in some examples, 1100 W or less, in someexamples, about 1090 W. In some examples, the curing of the overcoatcomposition under UV irradiation is performed with a UV output power of500 W or more, in some examples, 600 W or more, in some examples, 700 Wor more, in some examples 800 W or more, in some examples, 900 W ormore, in some examples, 1000 W or more. In some examples, the curing ofthe overcoat composition under UV irradiation is performed with a UVoutput power of 500 W to 2500 W, in some examples, 600 W to 2000 W, insome examples, 700 W to 1800 W, in some examples, 800 W to 1500 W, insome examples, 900 W to 1200 W. In some examples, the UV output powermay refer to the power received by the UV source, for example, a UV lampor a UV bulb and/or the power consumed by the UV source in emitting theUV irradiation and may also be referred to as the input intensity.

In some examples, the curing of the overcoat composition under UVirradiation is performed with a UV output intensity at the surface ofthe substrate, that is, an effective energy at the surface (sometimesreferred to as the dosage) of 40 mJ/cm² or less, in some examples, 35mJ/cm² or less, in some examples, 30 mJ/cm² or less, in some examples,25 mJ/cm² or less, in some examples, 20 mJ/cm² or less, in someexamples, 15 mJ/cm² or, in some examples, 10 mJ/cm². In some examples,the curing of the overcoat composition under UV irradiation is performedwith a UV output intensity at the surface of the substrate of 1 mJ/cm²or more, in some examples, 2 mJ/cm² or more, in some examples, 3 mJ/cm²or more, in some examples, 4 mJ/cm² or more or, in some examples, 5mJ/cm² or more. In some examples, the curing of the overcoat compositionunder UV irradiation is performed with a UV output intensity of 1 mJ/cm²to 40 mJ/cm², in some examples, 2 mJ/cm² to 35 mJ/cm², in some examples,3 mJ/cm² to 35 mJ/cm², in some examples, 4 mJ/cm² to 30 mJ/cm², in someexamples, 5 mJ/cm² to 25 mJ/cm², in some examples, 5 mJ/cm² to 20 mJ/cm²or, in some examples, 5 mJ/cm² to 15 mJ/cm².

In some examples, the UV irradiation is applied for 10 seconds or less,in some examples, 5 seconds or less, in some examples, 2.5 seconds orless, in some examples, 1 second or less, in some examples, 750milliseconds or less, in some examples, about 660 milliseconds. In someexamples, the UV irradiation is applied for 10 milliseconds or more, insome examples, 50 milliseconds or more, in some examples 100milliseconds or more, in some examples, 150 milliseconds or more, insome examples, 200 milliseconds or more, in some examples, 250milliseconds or more, 300 milliseconds or more, in some examples 350milliseconds or more, in some examples, 400 milliseconds or more, insome examples, 450 milliseconds or more, in some examples, 500milliseconds or more, in some examples, 600 milliseconds more more, insome examples 650 milliseconds or more. In some examples, the UVirradiation is applied for 50 milliseconds to 10 seconds, in someexamples, 100 milliseconds to 5 seconds, in some examples, 200milliseconds to 2.5 seconds, in some examples, 300 milliseconds to 1second, in some examples, 400 milliseconds to 750 milliseconds.

In some examples, the UV curable monomers and/or oligomers are selectedfrom epoxide-containing molecules and alkene-containing molecules. Insome examples, the UV curable monomers and/or oligomers are selectedfrom molecules comprising a plurality of epoxide groups and moleculescomprising a plurality of alkene groups. As used herein, moleculescontaining a plurality of a certain type of group may comprise 2 ormore, in some examples, 3 or more or, in some examples, 4 or more ofthat type of group.

In some examples, the alkene-containing molecules may be selected fromstyrenes, acrylates, methacrylates, allyl-containing compounds,alkenylcarboxylic acids, alkenyl esters, alkenyl amides, dienes,alkenylcyanides, alkenylethers, urethanes, alkenyl alcohols, alkenylthiols, alkenyl halides or a combination thereof. In some examples, themolecules comprising a plurality of alkene groups may comprise styrenes,acrylates, methacrylates, allyl-containing compounds, alkenylcarboxylicacids, alkenyl esters, alkenyl amides, dienes, alkenylcyanides,alkenylethers, urethanes, alkenyl alcohols, alkenyl thiols, alkenylhalides or a combination thereof. In some examples, thealkene-containing molecules or molecules containing a plurality ofalkene groups may be acrylates or urethanes.

In some examples, the UV curable overcoat composition comprises UVcurable monomers. In some examples, the UV curable monomers are selectedfrom monofunctional monomers (such as isobornyl acrylate), bifunctionalmonomers (such as tripropylene glycol diacrylate) or trifunctionalmonomers (such as trimethylol propane triacrylate). The type of monomerincluded in the UV curable overcoat composition may affect the curingand/or coating properties, such as the flexibility, adhesiveness andviscosity.

In some examples, the UV curable overcoat composition comprises UVcurable oligomers. In some examples, the UV curable oligomers areselected from epoxy acrylates, epoxy methacrylates (such as those basedon Bisphenol or the like), urethane acrylates, urethane methacrylates,polyester acrylates, polyester methacrylates, acrylic methacrylates, ormethacrylic acrylates or the like.

In some examples, the UV curable overcoat composition comprises anacrylate selected from mono-, di-, tri- and tetra-acrylates. In someexamples, the UV curable overcoat composition comprises an acrylateselected from di-, tri- and tetra-acrylates.

In some examples, the UV curable overcoat composition comprises acompound selected from 2,2-bis(acryloyloxymethyl)butyl acrylate,2-[(acryloyloxy)methyl]-2-({2,2-bis[(acryloyloxy)methyl]butoxy}methyl)butylacrylate,oxydi-1,1-propanediyl bisacrylate, hexamethylene diacrylate,(1-methyl-1,2-ethanediyl)bis([oxy(methyl-2,1-ethanediyl)]diacrylate,2-(2,2-bis{[2-acryloyloxy)ethanoxy]methyl}butoxy)ethyl acrylate, and2,2-bis(acryloyloxymethyl)butylacrylate.

In some examples, the UV curable overcoat composition comprises anoligomer of 4,4′-(1-methylethylidene)bisphenol, (chloromethyl)oxiraneand acrylate.

In some examples, the UV curable overcoat composition comprises acompound selected from dipropylene glycol diacrylate,2,2-bis(acryloyloxymethyl)butyl acrylate, and(1-methyl-1,2-ethanediyl)bis[oxy(methyl-2,1-ethanediyl)]diacrylate.

In some examples, the UV curable overcoat composition comprises amixture of dipropylene glycol diacrylate,2,2-bis(acryloyloxymethyl)butyl acrylate,(1-methyl-1,2-ethanediyl)bis[oxy(methyl-2,1-ethanediyl)]diacrylate andan oligomer of 4,4′-(1-methylethylidene)bisphenol and(chloromethyl)oxirane acrylate.

In some examples, the UV curable overcoat composition comprises acrylateesters, such as monoacrylate esters, diacrylate esters, triacrylateesters, tetraacrylate esters. In some examples, the UV curable overcoatcomposition comprises triacrylate esters. In some examples, the UVcurable overcoat composition comprises glycol acrylate esters, such asglycol monoacrylate esters, glycol diacrylate esters, glycol triacrylateesters, glycol tetraacrylate esters. In some examples, the glycol may beselected from ethylene glycol and propylene glycol. In some examples,the UV curable overcoat composition comprises2-(2,2-bis{[2-acryloxy)ethoxy]methyl}butoxy ethyl acrylate.

In some examples, the UV curable overcoat composition compriseshydroxyalkyl acrylates. In some examples, the UV curable overcoatcomposition comprises hydroxymethyl acrylates, hydroxyethyl acrylates,hydroxypropyl acrylates, hydroxyliso-propyl acrylates, hydroxybutylacrylates, hydroxylisobutyl acrylates, hydroxyl-tert-butyl acrylates. Insome examples, the UV curable overcoat composition compriseshydroxypropyl acrylate.

In some examples, the UV curable overcoat composition comprisesalkyldiol diacrylates. In some examples, the UV curable overcoatcomposition comprises methanediol diacrylate, ethanedol diacrylate,propanediol diacrylate, butanediol diacrylate, pentanediol diacrylate,hexanediol diacrylate, heptanediol diacrylate, octanediol diacrylate. Insome examples, the UV curable overcoat composition comprises hexanediylbisacrylate, optionally, 1,6-hexanediol diacrylate.

In some examples, the UV curable overcoat composition comprisestriacrylate esters, alkyldiol diacrylates and hydroxyalkyl acrylates. Insome examples, the UV curable overcoat composition comprises2-(2,2-bis{[2-acryloxy)ethoxy]methyl}butoxy ethyl acrylate, hexanedioldiacrylate, and hydroxypropyl acrylate.

Slip Agents

In some examples, the overcoat composition may include a slip agent. Insome examples, the slip agent is an agent which, after application ofthe overcoat composition, effects a decrease over time of thecoefficient of friction of the applied overcoat composition. In someexamples, the slip agent is a non-ionic compound. In some examples, theslip agent is selected from: (a) esters, amides, alcohols and acids ofoils; (b) fluoro-containing polymers; and (c) silicon compounds. In someexamples, the slip agent is selected from: (a) esters, amides, alcoholsand acids of oils, which may be selected from aromatic or aliphatichydrocarbon oils, which may be selected from mineral oils, naphthenicoils and paraffinic oils; natural oils such as castor, corn, cottonseed,olive, rapeseed, soybean, sunflower, other vegetable and animal oils,and so on; and functionalized derivatives of these oils, which may beselected from, for example, polyol esters of monocarboxylic acids suchas glycerol monostearate, pentaerythritol monooleate, saturated andunsaturated fatty acid amides or ethylenebis(amides), such as oleamide,erucamide, linoleamide, and mixtures thereof, glycols, polyether polyolslike Carbowax, and adipic acid and sebacic acid; (b) fluoro-containingpolymers such as polytetrafluoroethylene, fluorine oils, fluorine waxesand so forth; and (c) silicon compounds such as silanes and siliconepolymers, including silicone oils, polydimethylsiloxane, andamino-modified polydimethylsiloxane.

In some examples, the slip agent comprises a silicon compound. In someexample, the silicon compound may be selected form silanes and siliconepolymers.

In some examples, the slip agent comprises a silicone polyether. In someexamples, the silicone polyether comprises a polyether grafted to apolysiloxane (known as a rake-type silicone); a block co-polymercomprising polyether blocks and polysiloxane blocks; or a trisiloxaneterminated polyether. In some examples, the silicone polyether comprisesa low molecular weight polymer of ethylene oxide and/or propylene oxide;and a methylated siloxane moiety.

In some examples, the slip agent comprises a methylated siloxane. Insome examples, the slip agent comprises a methylated siloxane polyether.In some examples, the methylated siloxane polyether is apolydimethylsiloxane-modified polyether.

In some examples, the slip agent comprises a compound selected fromsilicone acrylates, silicone methacrylates, acrylated alkyl siloxanes,methacrylated alkyl siloxanes, acrylated aryl siloxanes, methacrylatedaryl siloxanes, acrylated allyl siloxanes and methacrylated allylsiloxanes.

In some examples, the slip agent comprises a compound selected fromsilicone polyether acrylate and silicone poly ether methacrylate. Insome examples, the slip agent comprises a silicone polyether acrylate.In some examples, the silicone polyether acrylate comprises a polyetheracrylate grafted to a polysiloxane (known as a rake-type silicone); ablock co-polymer comprising polyether acrylate blocks and polysiloxaneblocks; or a trisiloxane terminated polyether acrylate. In someexamples, the silicone polyether comprises a low molecular weightpolymer of ethylene oxide and/or propylene oxide; and a methylatedsiloxane moiety.

In some examples, the UV curable overcoat composition comprises a slipagent in an amount of 15 wt. % or less, for example, 10 wt. % or less,for example, 5 wt. % or less or, for example, about 2.5 wt. %. In someexamples, the UV curable overcoat composition comprises organosilane inan amount of 0.1 wt. % or more, for example, 0.5 wt. % or more, forexample, 1 wt. % or more or, for example, 2 wt. % or more. In someexamples, the UV curable overcoat composition comprises organosilane inan amount of 0.5 to 15 wt. %, for example, 1 wt. % to 10 wt. % or, forexample, 2 wt. % to 5 wt. %.

Photoinitiator

The UV curable overcoat composition may comprise a photoinitiator. Thephotoinitiator may be any suitable photoinitiator. The photoinitiatormay be any photoinitiator conventionally used in UV curable overcoatcompositions. In some examples, the photoinitiator may be a type Iphotoinitiator, that is, a photoinitiator that undergoes unimolecularbond cleavage on irradiation to yield free radicals, or a type IIphotoinitiator, that is, a photoinitiator that undergoes a bimolecularreaction in which the excited state of the photoinitiator interacts witha second molecule (a co-initiator) to generate free radicals. In someexamples, the type I photoinitiator may be a benzoin ester, a benzylketal, an α-dialkoxyacetophenone, a hydroxyalkylphenone, anα-aminoalkylphenone, or an acylphosphine oxide. In some examples, thetype II photoinitiator may be a benzophenone/amine or athioxanthone/amine. In some examples, the photoinitiator may bebenzophenone.

In some examples, the UV curable overcoat composition comprises aphotoinitiator in an amount of 5 wt. % or less, in some examples, 4 wt.% or less, in some examples, 3 wt. % or less, in some examples, 2 wt. %or less, in some examples, 1 wt. % or less, in some examples, 0.5 wt. %or less. In some examples, the UV curable overcoat composition comprisesphotoinitiator in an amount of 0.001 wt. % or more, in some examples,0.01 wt. % or more, in some examples, 0.1 wt. % or more, in someexamples, 0.2 wt. % or more. In some examples, the UV curable overcoatcomposition comprises photoinitiator in an amount of 0.001 to 5 wt. %,in some examples, 0.01 to 4 wt. %, in some examples, 0.1 to 3 wt. %.

Printed Label Substrate

The printed label substrate may comprise a label substrate and anelectrostatically printed ink disposed on the label substrate. In someexamples, the printed label substrate may comprise a primer disposedbetween the label substrate and the electrostatically printed ink. Insome examples, the printed label substrate may comprise a labelsubstrate, a primer disposed on the label substrate and anelectrostatically printed ink disposed on the primer.

In some examples, the printed label substrate may comprise an adhesivelayer disposed on the opposing surface of the label substrate to theelectrostatically printed ink. In some examples, the label substrate maycomprise an adhesive layer disposed on the opposing surface of the labelsubstrate to the surface onto which the electrostatically printed inkwill be disposed.

Label Substrate

The label substrate may be any substrate suitable for use in a label.The label substrate may be any suitable substrate capable of having anelectrostatic printing ink printed thereon. The label substrate may beany suitable substrate capable of having a primer applied thereon towhich an electrostatic printing ink may be printed.

The label substrate may comprise a material selected from an organic orinorganic material. The label substrate may include a natural polymericmaterial, for example, cellulose. The label substrate may include asynthetic polymer material, for example, a polymer formed from alkylenemonomers, including, for example, polyethylene and polypropylene, andco-polymers, such as styrene-polybutadiene. In some examples, thepolypropylene may be biaxially oriented polypropylene. In some examples,the label substrate comprises polyethylene.

In some examples, the label substrate may be or comprise a cellulosicsubstrate, such as a cellulosic paper. In some examples, the cellulosicsubstrate may be or comprise an uncoated cellulosic substrate, that is,absent of a coating of a polymeric material. In some examples, thecellulosic substrate, which may be a cellulosic paper, is coated with apolymeric material, for example, a polymer formed from styrene-butadieneresin. In some examples, the cellulosic paper has an inorganic materialbound to its surface (before any primer layer is applied) with apolymeric material, wherein the inorganic material may be selected from,for example, kaolinite or calcium carbonate.

The label substrate may be or comprise an acrylic substrate, in someexamples, a coated acrylic substrate, for example, coated with astyrene-butadiene co-polymer.

In some examples, the label substrate may be a transparent labelsubstrate. In some examples, the label substrate and the adhesive layer,once it has been adhered to a second substrate, may be transparent.

In some examples, the label substrate may comprise a polymeric material.In some examples, the polymeric material may comprise a transparentpolymeric material. In some examples, the label substrate may comprise afilm, for example, a thin film, of a polymeric material. In someexamples, the polymeric material may comprise a polymer formed fromalkylene monomers, including, for example, polyethylene andpolypropylene, and co-polymers such as styrene-polybutadiene. In someexamples, the polymeric material may comprise polyethylene (PE), linearlow density polyethylene (LLDPE), low density polyethylene (LDPE),medium density polyethylene (MDPE), high density polyethylene (HDPE),polypropylene (PP), cast (cPP) polypropylene or biaxially orientedpolypropylene (BOPP, oriented polyamide (OPA) or polyethyleneterephthalate (PET).

In some examples, the label substrate may comprise a polymeric materialhaving disposed thereon a primer. In some examples, the printed labelsubstrate may comprise a polymeric material having disposed thereon aprimer, wherein the primer is disposed between the polymer material andthe electrostatically printed ink.

In some examples, the label substrate may be or comprise a metal, whichmay be in sheet form. In some examples, the label substrate may comprisea metallic foil or a metallized substrate. In some examples, the labelsubstrate may comprise a metallized paper (i.e., paper having a metallayer thereon) or a metallized plastic film (i.e., plastic film having ametal layer thereon). In some examples, the metal may be selected fromor made from, for example, aluminium (Al), silver (Ag), tin (Sn), copper(Cu), or mixtures thereof. In some examples, the label substrate maycomprise an aluminium foil.

In some examples, the label substrate may comprise a plurality of layersof material, in some examples, a plurality of layers of film materiallaminated together. In some examples, the label substrate may comprise aplurality of layers of material selected from polymeric materials (e.g.,polymeric materials selected from PE, LLDPE, MDPE, PP, BOPP, PET andOPA), metallic materials (e.g., metallic foils such as aluminium foil,or metallized films such as metallized-PET (met-PET), or metallized-BOPP(met-BOPP), or metallized paper (met-paper) or any other metallizedsubstrate), paper and combinations thereof. In some examples, the labelsubstrate comprises a plurality of layers of film of a polymericmaterial, such as a combination of films selected from PE, LLDPE, MDPE,PP, BOPP, PET and OPA, laminated together to form a pre-laminated labelsubstrate. In some examples, the pre-laminated label substrate maycomprise a metallic layer, such as an aluminium layer. In some examples,the pre-laminated label substrate may comprise a paper-Al-PE, PET-Al-PE,BOPP-met-BOPP or PET-PE laminate.

In some examples, the label substrate may comprise a metallized paper inthe form of a paper substrate coated on at least one surface with alayer of metal, for example, aluminium. In some examples, the labelsubstrate may comprise a metallized polymeric film in the form of apolymer substrate coated on at least one surface with a layer of metal,for example, aluminium. In some examples, the label substrate comprisesa metallized polymeric film in the form of a metallized BOPP film or ametallized PET film.

In some examples, the label substrate may comprise a thin film ofmaterial, wherein the film has a thickness of 600 μm or less, in someexamples, 250 μm or less, in some examples, 200 μm or less, in someexamples, 150 μm or less, in some examples, 100 μm or less, in someexamples, 95 μm or less, in some examples, 90 μm or less, in someexamples, 85 μm or less, in some examples, 80 μm or less. In someexamples, the film of material has a thickness of about 80 μm. In someexamples, the film of material has a thickness of about 60 μm.

In some examples, the label substrate may comprise a thin film ofmaterial, wherein the film has a thickness of 5 μm or more, in someexamples, 10 μm or more, in some examples, 15 μm or more, in someexamples, 20 μm or more, in some examples, 25 μm or more, in someexamples, 30 μm or more, in some examples, 35 μm or more, in someexamples, 40 μm or more, in some examples, 45 μm or more, in someexamples, 50 μm or more, in some examples, 55 μm or more, in someexamples, 60 μm or more.

Adhesive Layer

In some examples, the printed label may comprise an adhesive layerdisposed on the opposing surface of the printed label substrate to theelectrostatically printed ink. In some examples, the printed labelsubstrate may comprise an adhesive layer disposed on the opposingsurface of the label substrate to the electrostatically printed ink.

In some examples, the adhesive layer is applied to the surface of thelabel substrate before the printed label substrate is provided for themethod of providing a printed label. In some examples, the adhesivelayer is applied to the surface of the label substrate before, during orafter the application of the UV curable overcoat composition. In someexamples, the adhesive layer is applied to the surface of the labelsubstrate before, during or after the application (i.e., printing) ofthe electrostatically printed ink. In some examples, the adhesive layeris applied to the surface of the label substrate before, during or afterthe application of the primer layer to the surface of the labelsubstrate.

In some examples, a removable release layer is applied to the adhesivelayer. In some examples, the removable release layer is applied at thesame time as the adhesive layer is applied. In some examples, theremovable release layer is applied immediately after the adhesive layeris applied. In some examples, the removable release layer is appliedafter the adhesive layer is applied but prior to the next layer beingapplied to the opposing surface of the label substrate.

In some examples, the adhesive layer is a pressure-sensitive adhesivelayer, a heat-sensitive adhesive layer, a contact adhesive layer, adrying adhesive layer (that is, an adhesive that adheres on drying), aradiation-curing adhesive layer (e.g., a UV-curing adhesive layer) or amoisture-curing adhesive layer (e.g., an adhesive that cures by reactingwith moisture present, for example, on a second surface to which thelabel is, in use, applied or adhered, or in the air). The pressuresensitive adhesive may be a hot melt pressure sensitive adhesive, suchas, for example, a rubber-based or acrylic-based pressure sensitiveadhesive. The adhesive could be based on a rubber-based hot meltcomposition, a solvent rubber adhesive, a solvent acrylic adhesive, or asolvent polyurethane adhesive. The adhesive could be emulsion-based,such as an emulsion acrylic adhesive.

In some examples, the adhesive layer is 100 μm or less in thickness, forexample, 90 μm or less in thickness, 80 μm or less in thickness, 70 μmor less in thickness, 60 μm or less in thickness, 50 μm or less inthickness, 40 μm or less in thickness, 30 μm or less in thickness, 20 μmor less in thickness, or 15 μm or less in thickness.

In some examples, the adhesive layer is 15 μm or more in thickness, 20μm or more in thickness, 30 μm or more in thickness, 40 μm or more inthickness, 50 μm or more in thickness, 60 μm or more in thickness, 70 μmor more in thickness, 80 μm or more in thickness, 90 μm or more inthickness, in some examples, 100 μm or more in thickness.

Primer

In some examples, the printed label substrate may comprise a primerdisposed between the label substrate and the electrostatically printedink.

In some examples, the printed label substrate is provided by applying aprimer to the label substrate, for example, to a surface of the labelsubstrate, and then by applying (i.e., printing) an electrostaticprinting ink on the primer. Thus, a printed label substrate havingdisposed thereon an electrostatically printed ink and a primer disposedbetween the label substrate and the electrostatically printed ink isformed.

The primer may comprise a primer resin. When it is applied, the primerresin may comprise a cross-linkable primer resin. The primer resin inthe printed label may comprise a cross-linked primer resin.

In a printed label, the primer resin may be a cross-linked primer resin.In the method of providing a printed label substrate, the primer resinmay be a cross-linkable primer resin until after the primer resin isapplied.

In some examples, the primer resin may be selected from the groupcomprising or consisting of hydroxyl containing resins, carboxylic groupcontaining resins, amine based polymer formulations, and combinationsthereof. In some examples, a hydroxyl containing resin may be selectedfrom polyvinyl alcohol resins, for example, polyvinyl alcohol basedpolyvinyl butyral formulations (such as Butvar resins from Eastman),Vinnol® (from Wacker polymers), cellulose derivative additives (fromEastman), polyester resins (such as Dynapol from Evonic) andpolyurethane-based formulations with hydroxyl groups. In some examples,the carboxylic group containing resins may be selected from olefinco-acrylic or methacrylic acid based copolymers, polyacrylic acid basedpolymers, and polylactic acid based polymers. In some examples, thecopolymer is a copolymer of ethylene and an acid selected from acrylicacid or methacrylic acid, and, in some examples, acid selected fromacrylic acid or methacrylic acid is present in the resin in an amount offrom 10 wt % to 50 wt %, in some examples 20 to 40 wt %. In someexamples, the amine based polymer formulations may be selected frompolyamines and polyethylene imines. The primer resin may be selectedfrom the group comprising, or consisting of, a polyvinyl alcohol resin,cellulose based resins, a polyester, a polyamine, a polyethylene imineresin, polyamide resin, polyurethane, copolymers of an alkylene monomerand an acrylic or methacrylic acid monomer, and polyacrylic polymers.

In some examples, the primer resin comprises a carboxylic functionalgroup, an amine functional group or a polyol functional group, or acombination thereof. In some examples, the primer resin comprises anamine functional group or a carboxylic functional group.

In some examples, the primer resin comprises an amine functional group.In some examples, the primer resin comprises or consists of apolyethylene imine resin.

The resin may have been crosslinked with a cross-linker, e.g. across-linker selected from melamine formaldehyde resin, phenolformaldehyde resins, polyethyleneimine and Zn and Zr complexes.

Examples of materials suitable for use as a primer include MichelmanDigiPrime® 050 or Michelman DigiPrime® 030.

In some examples, the primer on the printed label substrate of theprinted label comprises a cross-linked primer resin.

In some examples, the primer is applied or has been applied in an amountsuch that the coat weight of the primer on the label substrate is 0.01g/m² or more, in some examples, 0.05 g/m² or more, in some examples, 0.1g/m² or more, in some examples, in some examples, 0.14 g/m² or more,0.15 g/m² or more, in some examples, about 0.18 g/m². In some examples,the primer is applied or has been applied in an amount such that thecoat weight of the primer resin on the label substrate is up to about0.2 g/m², in some examples, up to about 0.5 g/m², in some examples, upto about 1 g/m², in some examples, up to about 1.5 g/m².

Electrostatically Printed Ink

In some examples, the printed label substrate has disposed thereon anelectrostatically printed ink. In some examples, the printed labelsubstrate has disposed thereon a printed ink, which may be anelectrostatically printed ink.

In some examples, the printed label substrate is provided by applying(i.e., printing) an electrostatic printing ink on the label substrate,for example, on a surface of the label substrate. Thus, a printed labelsubstrate having disposed thereon an electrostatically printed ink isformed.

In some examples, the electrostatically printed ink may be present in anamount such that the coat weight of electrostatically printed inkmeasured over the surface of the label substrate is at least 0.01 g/m²,in some examples, at least 0.05 g/m², in some examples, at least 0.1g/m², in some examples, at least 0.5 g/m², in some examples, at leastabout 1 g/m². In some examples, the electrostatically printed ink may bepresent in an amount such that the coat weight of electrostaticallyprinted ink measured over the surface of the label substrate is up toabout 16 g/m², in some examples, up to about 10 g/m², in some examples,up to about 5 g/m², in some examples, up to about 4 g/m².

Electrostatic Printing Ink

Electrostatic printing, for example, liquid electrostatic printing, isone method by which images or information can be printed ontosubstrates, such as label substrates. The electrostatic printing processgenerally involves creating an image on a photoconductive surface,applying a liquid electrostatic ink or a dry toner having chargedparticles to the photoconductive surface, such that they selectivelybind to the image, and then transferring the charged particles in theform of the image to a substrate, such as a label substrate.

The electrostatic printing ink may be electrostatically printed onto thelabel substrate. In some examples, the electrostatic printing ink may beelectrostatically printed onto the label substrate, thus forming theelectrostatically printed ink. In some examples, the electrostaticprinting ink may be electrostatically printed onto the primer, which hasbeen applied onto the label substrate.

The electrostatic printing ink may comprise a thermoplastic resin. Theelectrostatic printing ink may comprise a cross-linkable thermoplasticresin. The electrostatically printed ink (i.e., the electrostaticprinting ink after it has been electrostatically printed) may comprise across-linked thermoplastic resin. In the printed label, theelectrostatically printed ink may comprise a cross-linked thermoplasticresin.

In some examples, the electrostatic printing ink may be a liquidelectrostatic printing ink or a powder toner, that is, a dry toner foruse in dry electrostatic printing. In some examples, theelectrostatically printed ink may have been a liquid electrostaticprinting ink or a powder toner prior to printing.

The electrostatically printed ink disposed on a surface of the labelsubstrate may have been printed using a liquid electrostatic printingprocess. In some examples, the electrostatic printing ink may comprise acolorant or pigment and a thermoplastic resin. In some examples, theelectrostatic printing ink may be a liquid electrostatic printing ink,which may comprise a colorant or pigment, a thermoplastic resin and acarrier liquid. The liquid electrostatic printing ink may furthercomprise an additive such as a charge director, charge adjuvant,surfactant, viscosity modifier, emulsifier and the like.

In some examples, the colorant is a pigment. In some examples, theliquid electrostatic printing ink may not contain any pigment, or maycomprise substantially zero pigment and thus be a pigment-freecomposition, which may be useful in providing a particular transparentgloss or sheen to a label substrate.

In some examples, after printing, a liquid electrostatic printing ink(i.e., the liquid electrostatically printed ink) may comprise a reducedamount of carrier liquid compared with the liquid electrostatic printingink before printing. In some examples, the liquid electrostaticallyprinted ink may be substantially free from carrier liquid. Substantiallyfree from carrier liquid may indicate that the printed ink contains 5wt. % or less carrier liquid, in some examples, 2 wt. % or less carrierliquid, in some examples, 1 wt. % or less carrier liquid, in someexamples, 0.5 wt. % or less carrier liquid. In some examples, theelectrostatically printed ink is free from carrier liquid.

Each of these components of an electrostatic printing ink will bedescribed separately in the sub-sections which follow.

Thermoplastic Resin:

The thermoplastic resin may be referred to as a polymer resin or athermoplastic polymer. In some examples, the thermoplastic resin of theelectrostatic printing ink comprises a carboxylic functional group, anamine functional group, a polyol functional group or a combinationthereof. In some examples, the thermoplastic resin of the electrostaticprinting ink comprises a carboxylic functional group. In some examples,the thermoplastic resin of the electrostatic printing ink comprises anamine functional group. In some examples, the thermoplastic resin of theelectrostatic printing ink comprises a polyol functional group.

In some examples, the thermoplastic resin comprises or consists of apolymer having acidic side groups. In some examples, the acidic sidegroups may be in free acid form or may be in the form of an anion andassociated with a counterion, generally a metal counterion, for example,a metal selected from the alkali metals, such as lithium, sodium andpotassium, alkali earth metals, such as magnesium or calcium, andtransition metals, such as zinc.

In some examples, the thermoplastic resin may be a copolymer of analkylene monomer and a monomer selected from acrylic acid andmethacrylic acid. The thermoplastic resin having acidic side groups canbe selected from resins such as co-polymers of ethylene and anethylenically unsaturated acid of either acrylic acid or methacrylicacid; and ionomers thereof, such as methacrylic acid andethylene-acrylic or methacrylic acid co-polymers that are at leastpartially neutralized with metal ions (e.g., Zn, Na, Li), such asSURLYN® ionomers. The thermoplastic resin comprising acidic side groupscan be a co-polymer of ethylene and an ethylenically unsaturated acid ofeither acrylic or methacrylic acid, where the ethylenically unsaturatedacid of either acrylic or methacrylic acid may constitute from 5 wt. %to about 25 wt. % of the co-polymer, in some examples, from 10 wt. % toabout 20 wt. % of the co-polymer.

In some examples, the thermoplastic resin of the electrostatic printingink comprises polyolefin co-polymers, polyethylene co-acrylicco-polymers, polyethylene co-methacrylic co-polymers, polyethyleneco-vinyl acetate co-polymers, ionomers, or combinations thereof. In someexamples, the thermoplastic resin of the electrostatic printing inkcomprises or consists of alkylene acrylic or methacrylic acid resins,polyurethane resins, polyethylene imine resins, polyamide resins,polyvinyl alcohol resins, and combinations thereof.

In some examples, the thermoplastic resin may comprise ethylene orpropylene acrylic acid co-polymers; ethylene or propylene methacrylicacid co-polymers; ethylene vinyl acetate co-polymers; co-polymers ofethylene or propylene (e.g., 80 wt. % to 99.9 wt. %), and alkyl (e.g.,C1 to C5) ester of methacrylic or acrylic acid (e.g., 0.1 wt. % to 20wt. %); co-polymers of ethylene (e.g., 80 wt. % to 99.9 wt. %), acrylicor methacrylic acid (e.g., 0.1 wt. % to 20.0 wt. %) and alkyl (e.g., C1to C5) ester of methacrylic or acrylic acid (e.g., 0.1 wt. % to 20 wt.%); co-polymers of ethylene or propylene (e.g., 70 wt. % to 99.9 wt. %)and maleic anhydride (e.g., 0.1 wt. % to 30 wt. %); polyethylene;polystyrene; isotactic polypropylene (crystalline); co-polymers ofethylene ethyl acrylate; polyesters; polyvinyl toluene; polyamides;styrene/butadiene co-polymers; epoxy resins; acrylic resins (e.g.,co-polymer of acrylic or methacrylic acid and at least one alkyl esterof acrylic or methacrylic acid wherein alkyl may have from 1 to about 20carbon atoms, such as methyl methacrylate (e.g., 50 wt. % to 90 wt.%)/methacrylic acid (e.g., 0 wt. % to 20 wt. %)/ethylhexylacrylate(e.g., 10 wt. % to 50 wt. %); ethylene-acrylate terpolymers:ethylene-acrylic esters-maleic anhydride (MAH) or glycidyl methacrylate(GMA) terpolymers; ethylene-acrylic acid ionomers or combinationsthereof.

The thermoplastic resin may comprise a polymer having acidic sidegroups. The polymer having acidic side groups may have an acidity of 50mg KOH/g or more, in some examples, an acidity of 60 mg KOH/g or more,in some examples, an acidity of 70 mg KOH/g or more, in some examples,an acidity of 80 mg KOH/g or more, in some examples, an acidity of 90 mgKOH/g or more, in some examples, an acidity of 100 mg KOH/g or more, insome examples, an acidity of 105 mg KOH/g or more, in some examples, 110mg KOH/g or more, in some examples, 115 mg KOH/g or more. The polymerhaving acidic side groups may have an acidity of 200 mg KOH/g or less,in some examples, 190 mg or less, in some examples, 180 mg or less, insome examples, 130 mg KOH/g or less, in some examples, 120 mg KOH/g orless. The acidity of a polymer in mg KOH/g can be measured by usingstandard procedures, for example, by using the procedure described inASTM D1386.

The thermoplastic resin may comprise a polymer having acidic side groupsthat has a melt flow rate of about 70 g/10 minutes or less, in someexamples, about 60 g/10 minutes or less, in some examples, about 50 g/10minutes or less, in some examples, about 40 g/10 minutes or less, insome examples, 30 g/10 minutes or less, in some examples, 20 g/10minutes or less, in some examples, 10 g/10 minutes or less. In someexamples, all polymers having acidic side groups and/or ester groups inthe particles each individually have a melt flow rate of 90 g/10 minutesor less, in some examples, 80 g/10 minutes or less, in some examples, 70g/10 minutes or less, in some examples, 60 g/10 minutes or less.

The polymer having acidic side groups can have a melt flow rate of about10 g/10 minutes to about 120 g/10 minutes, in some examples, about 10g/10 minutes to about 70 g/10 minutes, in some examples, about 10 g/10minutes to about 40 g/10 minutes, in some examples, about 20 g/10minutes to about 30 g/10 minutes. The polymer having acidic side groupscan have a melt flow rate of, in some examples, about 50 g/10 minutes toabout 120 g/10 minutes, in some examples, about 60 g/10 minutes to about100 g/10 minutes. The melt flow rate can be measured using standardprocedures, for example, as described in ASTM D1238.

The acidic side groups may be in free acid form or may be in the form ofan anion and associated with a counterion, generally metal counterions,for example, a metal selected from the alkali metals, such as lithium,sodium and potassium, alkali earth metals, such as magnesium or calcium,and transition metals, such as zinc. The thermoplastic resin havingacidic sides groups can be selected from resins such as co-polymers ofethylene and an ethylenically unsaturated acid of either acrylic acid ormethacrylic acid; and ionomers thereof, such as methacrylic acid andethylene-acrylic or methacrylic acid co-polymers that are at leastpartially neutralized with metal ions (e.g., Zn, Na, Li) such as SURLYN®ionomers. The polymer comprising acidic side groups can be a co-polymerof ethylene and an ethylenically unsaturated acid of either acrylic ormethacrylic acid, in which the ethylenically unsaturated acid of eitheracrylic or methacrylic acid constitutes from 5 wt. % to about 25 wt. %of the co-polymer, in some examples, from 10 wt. % to about 20 wt. % ofthe co-polymer.

The thermoplastic resin may comprise two different polymers havingacidic side groups. The two polymers having acidic side groups may havedifferent acidities, which may fall within the ranges mentioned above.The thermoplastic resin may comprise a first polymer having acidic sidegroups that has an acidity of from 10 mg KOH/g to 110 mg KOH/g, in someexamples, 20 mg KOH/g to 110 mg KOH/g, in some examples, 30 mg KOH/g to110 mg KOH/g, in some examples, 50 mg KOH/g to 110 mg KOH/g, and asecond polymer having acidic side groups that has an acidity of 110 mgKOH/g to 130 mg KOH/g.

The thermoplastic resin may comprise two different polymers havingacidic side groups: a first polymer having acidic side groups that has amelt flow rate of about 10 g/10 minutes to about 50 g/10 minutes and anacidity of from 10 mg KOH/g to 110 mg KOH/g, in some examples, 20 mgKOH/g to 110 mg KOH/g, in some examples, 30 mg KOH/g to 110 mg KOH/g, insome examples, 50 mg KOH/g to 110 mg KOH/g, and a second polymer havingacidic side groups that has a melt flow rate of about 50 g/10 minutes toabout 120 g/10 minutes and an acidity of 110 mg KOH/g to 130 mg KOH/g.The first and second polymers may be absent of ester groups.

In some examples, the ratio of the first polymer having acidic sidegroups to the second polymer having acidic side groups can be from about10:1 to about 2:1. In some examples, the ratio can be from about 6:1 toabout 3:1, in some examples, about 4:1.

The thermoplastic resin may comprise a polymer having a melt viscosityof 15000 poise or less, in some examples, a melt viscosity of 10000poise or less, in some examples, 1000 poise or less, in some examples,100 poise or less, in some examples, 50 poise or less, in some examples,10 poise or less; said polymer may be a polymer having acidic sidegroups as described herein. The thermoplastic resin may comprise a firstpolymer having a melt viscosity of 15000 poise or more, in someexamples, 20000 poise or more, in some examples, 50000 poise or more, insome examples, 70000 poise or more; and in some examples, the polymerresin may comprise a second polymer having a melt viscosity less thanthe first polymer, in some examples, a melt viscosity of 15000 poise orless, in some examples, a melt viscosity of 10000 poise or less, in someexamples, 1000 poise or less, in some examples, 100 poise or less, insome examples, 50 poise or less, and in some examples, 10 poise or less.The thermoplastic resin may comprise a first polymer having a meltviscosity of more than 60000 poise, in some examples, from 60000 poiseto 100000 poise, in some examples, from 65000 poise to 85000 poise; asecond polymer having a melt viscosity of from 15000 poise to 40000poise, in some examples, 20000 poise to 30000 poise, and a third polymerhaving a melt viscosity of 15000 poise or less, in some examples, a meltviscosity of 10000 poise or less, in some examples, 1000 poise or less,in some examples, 100 poise or less, in some examples, 50 poise or less,in some examples, 10 poise or less; an example of the first polymer isNucrel 960 (from DuPont), an example of the second polymer is Nucrel 699(from DuPont), and an example of the third polymer is AC-5120 or AC-5180(from Honeywell). The first, second and third polymers may be polymershaving acidic side groups as described herein. The melt viscosity can bemeasured by using a rheometer, for example, a commercially availableAR-2000 Rheometer from Thermal Analysis Instruments, by using thegeometry of 25 mm steel plate-standard steel parallel plate, and findingthe plate over plate rheometry isotherm at 120° C., 0.01 Hz shear rate.

If the thermoplastic resin comprises a single type of polymer, thepolymer (excluding any other components of the electrostatic inkcomposition) may have a melt viscosity of 6000 poise or more, in someexamples, a melt viscosity of 8000 poise or more, in some examples, amelt viscosity of 10000 poise or more, in some examples, a meltviscosity of 12000 poise or more. If the thermoplastic resin comprises aplurality of polymers all of the polymers of the thermoplastic resin maytogether form a mixture (excluding any other components of theelectrostatic ink composition) that has a melt viscosity of 6000 poiseor more, in some examples, a melt viscosity of 8000 poise or more, insome examples, a melt viscosity of 10000 poise or more, in someexamples, a melt viscosity of 12000 poise or more. Melt viscosity can bemeasured by using standard techniques. The melt viscosity can bemeasured by using a rheometer, for example, a commercially availableAR-2000 Rheometer from Thermal Analysis Instruments, by using thegeometry of 25 mm steel plate-standard steel parallel plate, and findingthe plate over plate rheometry isotherm at 120° C., 0.01 Hz shear rate.

The thermoplastic resin may comprise two different polymers havingacidic side groups that are selected from co-polymers of ethylene and anethylenically unsaturated acid of either acrylic acid or methacrylicacid; or ionomers thereof, such as methacrylic acid and ethylene-acrylicor methacrylic acid co-polymers which are at least partially neutralizedwith metal ions (e.g., Zn, Na, Li) such as SURLYN® ionomers. Thethermoplastic resin may comprise (i) a first polymer that is aco-polymer of ethylene and an ethylenically unsaturated acid of eitheracrylic acid or methacrylic acid, wherein the ethylenically unsaturatedacid of either acrylic or methacrylic acid constitutes from 8 wt. % toabout 16 wt. % of the co-polymer, in some examples, 10 wt. % to 16 wt. %of the co-polymer; and (ii) a second polymer that is a co-polymer ofethylene and an ethylenically unsaturated acid of either acrylic acid ormethacrylic acid, wherein the ethylenically unsaturated acid of eitheracrylic or methacrylic acid constitutes from 12 wt. % to about 30 wt. %of the co-polymer, in some examples, from 14 wt. % to about 20 wt. % ofthe co-polymer, in some examples, from 16 wt. % to about 20 wt. % of theco-polymer, and in some examples, from 17 wt. % to 19 wt. % of theco-polymer.

The thermoplastic resin may comprise a polymer having acidic sidegroups, as described above (which may be free of ester side groups), anda polymer having ester side groups. The polymer having ester side groupsmay be a thermoplastic polymer. The polymer having ester side groups mayfurther comprise acidic side groups. The polymer having ester sidegroups may be a co-polymer of a monomer having ester side groups and amonomer having acidic side groups. The polymer may be a co-polymer of amonomer having ester side groups, a monomer having acidic side groups,and a monomer absent of any acidic and ester side groups. The monomerhaving ester side groups may be a monomer selected from esterifiedacrylic acid or esterified methacrylic acid. The monomer having acidicside groups may be a monomer selected from acrylic or methacrylic acid.The monomer absent of any acidic and ester side groups may be analkylene monomer, including, for example, ethylene or propylene. Theesterified acrylic acid or esterified methacrylic acid maybe an alkylester of acrylic acid or an alkyl ester of methacrylic acid,respectively. The alkyl group in the alkyl ester of acrylic ormethacrylic acid may be an alkyl group having 1 to 30 carbon atoms, insome examples, 1 to 20 carbon atoms, in some examples, 1 to 10 carbonatoms; in some examples, selected from methyl, ethyl, iso-propyl,n-propyl, t-butyl, iso-butyl, n-butyl and pentyl.

The polymer having ester side groups may be a co-polymer of a firstmonomer having ester side groups, a second monomer having acidic sidegroups and a third monomer which is an alkylene monomer absent of anyacidic and ester side groups. The polymer having ester side groups maybe a co-polymer of (i) a first monomer having ester side groups selectedfrom esterified acrylic acid or esterified methacrylic acid, in someexamples an alkyl ester of acrylic or methacrylic acid, (ii) a secondmonomer having acidic side groups selected from acrylic or methacrylicacid, and (iii) a third monomer which is an alkylene monomer selectedfrom ethylene and propylene. The first monomer may constitute 1% to 50%by weight of the co-polymer, in some examples, 5% to 40% by weight, insome examples, 5% to 20% by weight of the co-polymer, and in someexamples, 5% to 15% by weight of the co-polymer. The second monomer mayconstitute 1% to 50% by weight of the co-polymer, in some examples, 5%to 40% by weight of the co-polymer, in some examples, 5% to 20% byweight of the co-polymer, and in some examples, 5% to 15% by weight ofthe co-polymer. In some examples, the first monomer constitutes 5% to40% by weight of the co-polymer, the second monomer constitutes 5% to40% by weight of the co-polymer, with the third monomer constituting theremaining weight of the co-polymer. In some examples, the first monomerconstitutes 5% to 15% by weight of the co-polymer, the second monomerconstitutes 5% to 15% by weight of the co-polymer, with the thirdmonomer constituting the remaining weight of the co-polymer. In someexamples, the first monomer constitutes 8% to 12% by weight of theco-polymer, the second monomer constitutes 8% to 12% by weight of theco-polymer, with the third monomer constituting the remaining weight ofthe co-polymer. In some examples, the first monomer constitutes about10% by weight of the co-polymer, the second monomer constitutes about10% by weight of the co-polymer, with the third monomer constituting theremaining weight of the co-polymer. The polymer may be selected from theBynel® class of polymers, including Bynel 2022 and Bynel 2002, which areavailable from DuPont®.

The polymer having ester side groups may constitute 1% or more by weightof the total amount of the resin polymers, for example, thermoplasticresins, in the liquid electrostatic ink composition and/or theelectrostatic ink printed on the primer layer, for example, the totalamount of the polymer or polymers having acidic side groups and polymerhaving ester side groups. The polymer having ester side groups mayconstitute 5% or more by weight of the total amount of the resinpolymers, that is, the thermoplastic resin polymers, in some examples,8% or more by weight of the total amount of the resin polymers, forexample, thermoplastic resin polymers, in some examples, 10% or more byweight of the total amount of the resin polymers, for example,thermoplastic resin polymers, in some examples, 15% or more by weight ofthe total amount of the resin polymers, for example, thermoplastic resinpolymers, in some examples, 20% or more by weight of the total amount ofthe resin polymers, for example, thermoplastic resin polymers, in someexamples, 25% or more by weight of the total amount of the resinpolymers, for example, thermoplastic resin polymers, in some examples,30% or more by weight of the total amount of the resin polymers, forexample, thermoplastic resin polymers, in some examples, 35% or more byweight of the total amount of the resin polymers, for example,thermoplastic resin polymers, in the liquid electrostatic inkcomposition and/or the electrostatic ink printed on the primer layer.The polymer having ester side groups may constitute from 5% to 50% byweight of the total amount of the resin polymers, for example,thermoplastic resin polymers, in the liquid electrostatic compositionand/or the ink printed on the primer layer, in some examples, 10% to 40%by weight of the total amount of the resin polymers, for example,thermoplastic resin polymers, in the liquid electrostatic inkcomposition and/or the electrostatic ink composition printed on theprimer layer, in some examples, 5% to 30% by weight of the total amountof the resin polymers, for example, thermoplastic resin polymers, in theliquid electrostatic ink composition and/or the ink composition printedon the primer layer, in some examples, 5% to 15% by weight of the totalamount of the resin polymers, for example, thermoplastic resin polymers,in the liquid electrostatic ink composition and/or the ink compositionprinted on the primer layer, in some examples, 15% to 30% by weight ofthe total amount of the resin polymers, for example, thermoplastic resinpolymers, in the liquid electrostatic ink composition and/or the inkcomposition printed on the primer layer.

The polymer having ester side groups may have an acidity of 50 mg KOH/gor more, in some examples, an acidity of 60 mg KOH/g or more, in someexamples, an acidity of 70 mg KOH/g or more, in some examples, anacidity of 80 mg KOH/g or more. The polymer having ester side groups mayhave an acidity of 100 mg KOH/g or less, in some examples, 90 mg KOH/gor less. The polymer having ester side groups may have an acidity of 60mg KOH/g to 90 mg KOH/g, in some examples, 70 mg KOH/g to 80 mg KOH/g.

The polymer having ester side groups may have a melt flow rate of about10 g/10 minutes to about 120 g/10 minutes, in some examples, about 10g/10 minutes to about 50 g/10 minutes, in some examples, about 20 g/10minutes to about 40 g/10 minutes, in some examples, about 25 g/10minutes to about 35 g/10 minutes.

The polymer, polymers, co-polymer, or co-polymers of the thermoplasticresin can in some examples be selected from the Nucrel family of resins(e.g., Nucrel 403™, Nucrel 407™, Nucrel 609HS™, Nucrel 908HS™, Nucrel1202HC™, Nucrel 30707™, Nucrel 1214™, Nucrel 903™, Nucrel 3990™, Nucrel910™, Nucrel 925™, Nucrel 699™, Nucrel 599™, Nucrel 960™, Nucrel RX76™,Nucrel 2806™, Bynell 2002, Bynell 2014, Bynell 2020 and Bynell 2022(sold by E. I. du PONT)), the AC family of resins (e.g., AC-5120,AC-5180, AC-540, AC-580 (sold by Honeywell)), the Aclyn family of resins(e.g., Aclyn 201, Aclyn 246, Aclyn 285, Aclyn 295 (sold by Honeywell)),and the Lotader family of resins (e.g., Lotader 2210, Lotader, 3430, andLotader 8200 (sold by Arkema)).

The polymer resin can constitute about 5 to 90%, in some examples, about50 to 80%, by weight of the solids of the liquid electrostatic inkcomposition and/or the ink composition printed on the label substrate.The resin can constitute about 60 to 95%, in some examples, about 70 to95%, by weight of the solids of the liquid electrostatic ink compositionand/or the ink composition printed on the primer layer.

Colorant:

An electrostatically printed ink may comprise a colorant. Anelectrostatic printing ink may comprise a colorant. The colorant may bea dye or a pigment. The colorant can be any colorant compatible with theliquid carrier and useful for electrostatic printing. For example, thecolorant may be present as pigment particles or may comprise a resin (inaddition to the resins described herein) and a pigment. The resins andpigments can be any of those standardly used. In some examples, thecolorant is selected from a cyan pigment, a magenta pigment, a yellowpigment and a black pigment. For example, pigments by Hoechst includingPermanent Yellow DHG, Permanent Yellow GR, Permanent Yellow G, PermanentYellow NCG-71, Permanent Yellow GG, Hansa Yellow RA, Hansa BrilliantYellow 5GX-02, Hansa Yellow X, NOVAPERM® YELLOW HR, NOVAPERM® YELLOWFGL, Hansa Brilliant Yellow 10GX, Permanent Yellow G3R-01, HOSTAPERM®YELLOW H4G, HOSTAPERM® YELLOW H3G, HOSTAPERM® ORANGE GR, HOSTAPERM®SCARLET GO, Permanent Rubine F6B; pigments by Sun Chemical includingL74-1357 Yellow, L75-1331 Yellow, L75-2337 Yellow; pigments by Heubachincluding DALAMAR® YELLOW YT-858-D; pigments by Ciba-Geigy includingCROMOPHTHAL® YELLOW 3 G, CROMOPHTHAL® YELLOW GR, CROMOPHTHAL® YELLOW 8G, IRGAZINE® YELLOW SGT, IRGALITE® RUBINE 4BL, MONASTRAL® MAGENTA,MONASTRAL® SCARLET, MONASTRAL® VIOLET, MONASTRAL® RED, MONASTRAL®VIOLET; pigments by BASF including LUMOGEN® LIGHT YELLOW, PALIOGEN®ORANGE, HELIOGEN® BLUE L 690 IF, HELIOGEN® BLUE TBD 7010, HELIOGEN® BLUEK 7090, HELIOGEN® BLUE L 710 IF, HELIOGEN® BLUE L 6470, HELIOGEN® GREENK 8683, HELIOGEN® GREEN L 9140; pigments by Mobay including QUINDO®MAGENTA, INDOFAST® BRILLIANT SCARLET, QUINDO® RED 6700, QUINDO® RED6713, INDOFAST® VIOLET; pigments by Cabot including Maroon B STERLING®NS BLACK, STERLING® NSX 76, MOGUL® L; pigments by DuPont includingTIPURE® R-101; and pigments by Paul Uhlich including UHLICH® BK 8200. Insome examples, the pigment may be a white pigment. Where the pigment isa white pigment particle, the pigment particle may be selected from thegroup consisting of TiO₂, calcium carbonate, zinc oxide, and mixturesthereof. In some examples, the white pigment particle may comprise analumina-TiO₂ pigment.

In some examples, the colorant or pigment particles may have a medianparticle size or d₅₀ of 20 μm or less, for example, 15 μm or less, forexample, 10 μm or less, for example, 5 μm or less, for example, 4 μm orless, for example, 3 μm or less, for example, 2 μm or less, for example,1 μm or less, for example, 0.9 μm or less, for example, 0.8 μm or less,for example, 0.7 μm or less, for example, 0.6 μm or less, for example,0.5 μm or less. Unless otherwise stated, the particle size of thecolorant or pigment particle and the resin coated pigment particle isdetermined by using laser diffraction on a Malvern Mastersizer 2000according to the standard procedure as described in the operatingmanual.

The colorant or pigment particle may be present in an electrostatic inkcomposition in an amount of from 10 wt. % to 80 wt. % of the totalamount of resin and pigment, in some examples, 15 wt. % to 80 wt. %, insome examples, 15 wt. % to 60 wt. %, in some examples, 15 wt. % to 50wt. %, in some examples, 15 wt. % to 40 wt. %, in some examples, 15 wt.% to 30 wt. % of the total amount of resin and colorant. In someexamples, the colorant or pigment particle may be present in anelectrostatic ink composition in an amount of at least 50 wt. % of thetotal amount of resin and colorant or pigment, for example, at least 55wt. % of the total amount of resin and colorant or pigment.

Carrier Liquid:

Before and during printing of the electrostatic printing ink, theelectrostatic printing ink may comprise a carrier liquid. Generally, thecarrier liquid can act as a dispersing medium for the other componentsin the electrostatic printing ink. For example, the carrier liquid maycomprise or be a hydrocarbon, silicone oil, vegetable oil or the like.The carrier liquid may include, but is not limited to, an insulating,non-polar, non-aqueous liquid that can be used as a medium for tonerparticles. The carrier liquid can include compounds that have aresistivity in excess of about 10⁹ ohm·cm. The carrier liquid may have adielectric constant below about 5, in some examples, below about 3. Thecarrier liquid can include, but is not limited to, hydrocarbons. Thehydrocarbon can include, but is not limited to, an aliphatichydrocarbon, an isomerized aliphatic hydrocarbon, branched chainaliphatic hydrocarbons, aromatic hydrocarbons, and combinations thereof.Examples of the carrier liquids include, but are not limited to,aliphatic hydrocarbons, isoparaffinic compounds, paraffinic compounds,dearomatized hydrocarbon compounds, and the like. In particular, thecarrier liquids can include, but are not limited to, Isopar-G™,Isopar-H™, Isopar-L™, Isopar-M™, Isopar-K™, Isopar-V™, Norpar 12™,Norpar 13™, Norpar 15™, Exxol D40™, Exxol D80™, Exxol D100™, ExxolD130™, and Exxol D140™ (each sold by EXXON CORPORATION); Teclen N-16™,Teclen N-20™, Teclen N-22™, Nisseki Naphthesol L™, Nisseki NaphthesolM™, Nisseki Naphthesol H™, #0 Solvent L™, #0 Solvent M™, #0 Solvent H™,Nisseki Isosol 300™, Nisseki Isosol 400™, AF-4™, AF-SS™, AF-6™ and AF-7™(each sold by NIPPON OIL CORPORATION); IP Solvent 1620™ and IP Solvent2028™ (each sold by IDEMITSU PETROCHEMICAL CO., LTD.); Amsco OMS™ andAmsco 460™ (each sold by AMERICAN MINERAL SPIRITS CORP.); and Electron,Positron, New II, Purogen HF (100% synthetic terpenes) (sold byECOLINK™).

Before electrostatic printing, the carrier liquid can constitute about20% to 99.5% by weight of the electrostatic printing ink, in someexamples, 60% to 99.5% by weight of the electrostatic printing ink.Before printing, the carrier liquid may constitute about 40% to 90% byweight of the electrostatic printing ink. Before printing, the carrierliquid may constitute about 60% to 80% by weight of the electrostaticprinting ink. Before printing, the carrier liquid may constitute about90% to 99.5% by weight of the electrostatic printing ink, in someexamples, 95% to 99% by weight of the electrostatic printing ink.

The electrostatic printing ink, when electrostatically printed (that is,the electrostatically printed ink), may be substantially free fromcarrier liquid. In an electrostatic printing process and/or afterwards,the carrier liquid may be removed, for example, by an electrophoresisprocess during printing and/or evaporation, such that substantially justsolids are transferred to the label substrate. Substantially free fromcarrier liquid may indicate that the ink printed on the label substratecontains 5 wt. % or less carrier liquid, in some examples, 2 wt. % orless carrier liquid, in some examples, 1 wt. % or less carrier liquid,in some examples, 0.5 wt. % or less carrier liquid. In some examples,the electrostatically printed ink on the label substrate is free fromcarrier liquid.

Charge Director:

A liquid electrostatic printing ink and/or electrostatically printed inkmay comprise a charge director. A charge director can be added to anelectrostatic printing ink to impart a charge of a desired polarityand/or maintain sufficient electrostatic charge on the particles of anelectrostatic printing ink. The charge director may comprise ioniccompounds, including, for example, metal salts of fatty acids, metalsalts of sulfo-succinates, metal salts of oxyphosphates, metal salts ofalkyl-benzenesulfonic acid, metal salts of aromatic carboxylic acids orsulfonic acids, as well as zwitterionic and non-ionic compounds, such aspolyoxyethylated alkylamines, lecithin, polyvinylpyrrolidone, organicacid esters of polyvalent alcohols, and the like. The charge directormay be selected from oil-soluble petroleum sulfonates (e.g., neutralCalcium Petronate™, neutral Barium Petronate™, and basic BariumPetronate™) polybutylene succinimides (e.g., OLOA™ 1200 and Amoco 575),and glyceride salts (e.g., sodium salts of phosphate mono- anddiglycerides with unsaturated and saturated acid substituents), sulfonicacid salts including, for example, barium, sodium, calcium, andaluminium salts of sulfonic acid. The sulfonic acids may include, forexample, alkyl sulfonic acids, aryl sulfonic acids, and sulfonic acidsof alkyl succinates (e.g., see WO 2007/130069). The charge director mayimpart a negative charge or a positive charge on the resin-containingparticles of an electrostatic printing ink.

The charge director can comprise a sulfosuccinate moiety of the generalformula: [R_(a)—O—C(O)CH₂CH(SO₃ ⁻)C(O)—O—R_(d)], in which each of R_(a)and R_(b) is an alkyl group. In some examples, the charge directorcomprises nanoparticles of a simple salt and a sulfosuccinate salt ofthe general formula MA_(n), wherein M is a metal, n is the valence of M,and A is an ion of the general formula [R_(a)—O—C(O)CH₂CH(SO₃⁻)C(O)—O—R_(d)], in which each of R_(a) and R_(b) is an alkyl group, orother charge directors as found in WO 2007130069, which is incorporatedherein by reference in its entirety. As described in WO 2007130069, thesulfosuccinate salt of the general formula MA_(n) is an example of amicelle forming salt. The charge director may be substantially free ofor free of an acid of the general formula HA, in which A is as describedabove. The charge director may comprise micelles of said sulfosuccinatesalt enclosing at least some of the nanoparticles. The charge directormay comprise at least some nanoparticles having a size of 200 nm orless, in some examples, 2 nm or more. As described in WO 2007130069,simple salts are salts that do not form micelles by themselves, althoughthey may form a core for micelles with a micelle forming salt. The ionsconstructing the simple salts are all hydrophilic. The simple salt maycomprise a cation selected from Mg, Ca, Ba, NH₄, tert-butyl ammonium,Li⁺, and Al³⁺, or from any sub-group thereof. The simple salt maycomprise an anion selected from SO₄ ²⁻, PO³⁻, NO₃ ⁻, HPO₄ ²⁻, CO₃ ²⁻,acetate, trifluoroacetate (TFA), Cl⁻, Br, BFa⁻, F⁻, ClO₄ ⁻, and TiO₃ ⁴⁻,or from any sub-group thereof. The simple salt may be selected fromCaCO₃, Ba₂TiO₃, Al₂(SO₄), Al(NO₃)₃, Ca₃(PO₄)₂, BaSO₄, BaHPO₄, Ba₂(PO₄)₃,CaSO₄, (NH₄)₂CO₃, (NH₄)₂SO₄, NH₄OAc, tert-butyl ammonium bromide,NH₄NO₃, LiTFA, Al₂(SO₄)₃, LiClO₄, and LiBF₄, or any sub-group thereof.The charge director may further comprise basic barium petronate (BBP).

In the formula [R_(a)—O—C(O)CH₂CH(SO₃ ⁻)C(O)—O—R_(d)], in some examples,each of R_(a) and R_(b) is an aliphatic alkyl group. In some examples,each of R_(a) and R_(b) independently is a C625 alkyl group. In someexamples, said aliphatic alkyl group is linear. In some examples, saidaliphatic alkyl group is branched. In some examples, said aliphaticalkyl group includes a linear chain of 6 carbon atoms or more. In someexamples, R_(a) and R_(b) are the same. In some examples, at least oneof R_(a) and R_(b) is C₁₃H₂₇. In some examples, M is Na, K, Cs, Ca, orBa. The formula [R_(a)—O—C(O)CH₂CH(SO₃ ⁻)C(O)—O—R_(d)] and/or theformula MA_(n) may be as defined in any part of WO 2007130069.

The charge director may comprise (i) soya lecithin, (ii) a bariumsulfonate salt, such as basic barium petronate (BPP), and (iii) anisopropyl amine sulfonate salt. Basic barium petronate is a bariumsulfonate salt of a 21-26 carbon atom hydrocarbon alkyl chain, and canbe obtained, for example, from Chemtura. An example isopropyl aminesulphonate salt is dodecyl benzene sulfonic acid isopropyl amine, whichis available from Croda.

In an electrostatic printing ink, the charge director can constituteabout 0.001% to 20% by weight, in some examples, 0.01 to 20% by weight,in some examples, 0.01 to 10% by weight, in some examples, 0.01 to 1% byweight of the solids of an electrostatic printing ink and/or anelectrostatically printed ink. The charge director can constitute about0.001 to 0.15% by weight of the solids of a liquid electrostaticprinting ink and/or electrostatically printed ink, in some examples,0.001 to 0.15% by weight, in some examples, 0.001 to 0.02% by weight ofthe solids of a liquid electrostatic printing ink and/orelectrostatically printed ink. In some examples, a charge directorimparts a negative charge on an electrostatic printing ink. The particleconductivity may range from 50 to 500 pmho/cm, in some examples, from200-350 pmho/cm.

Charge Adjuvant:

A liquid electrostatic printing ink and/or electrostatically printed inkmay include a charge adjuvant. A charge adjuvant may be present with acharge director, and may be different to the charge director, and act toincrease and/or stabilise the charge on particles, for example,resin-containing particles of an electrostatic printing ink. The chargeadjuvant may include barium petronate, calcium petronate, Co salts ofnaphthenic acid, Ca salts of naphthenic acid, Cu salts of naphthenicacid, Mn salts of naphthenic acid, Ni slats of naphthenic acid, Zn saltsof naphthenic acid, Fe salts of naphthenic acid, Ba salts of stearicacid, Co salts of stearic acid, Pb salts of stearic acid, Zn salts ofstearic acid, Al salts of stearic acid, Cu salts of stearic acid, Fesalts of stearic acid, metal carboxylates (e.g., Al tristearate, Aloctanoate, Li heptanoate, Fe stearate, Fe distearate, Ba stearate, Crstearate, Mg octanoate, Ca stearate, Fe naphthenate, Zn naphthenate, Mnheptanoate, Zn heptanoate, Ba octanoate, Al octanoate, Co octanoate, Mnoctanoate, and Zn octanoate), Co lineolates, Mn lineolates, Pblineolates, Zn lineolates, Ca oleates, Co oleates, Zn palmirate, Caresinates, Co resinates, Mn resinates, Pb resinates, Zn resinates, ABdiblock co-polymers of 2-ethylhexyl methacrylate-co-methacrylic acidcalcium, and ammonium salts, co-polymers of an alkyl acrylamidoglycolatealkyl ether (e.g., methyl acrylamidoglycolate methyl ether-co-vinylacetate), and hydroxy bis(3,5-di-tert-butyl salicylic) aluminatemonohydrate. In some examples, the charge adjuvant is aluminium di-and/or tristearate and/or aluminium di- and/or tripalmitate.

The charge adjuvant may constitute about 0.1 to 5% by weight of thesolids of a liquid electrostatic printing ink and/or electrostaticallyprinted ink. The charge adjuvant may constitute about 0.5 to 4% byweight of the solids of a liquid electrostatic printing ink and/orelectrostatically printed ink. The charge adjuvant may constitute about1 to 3% by weight of the solids of a liquid electrostatic printing inkand/or electrostatically printed ink.

Other Additives:

In some examples, an electrostatic printing ink and/or electrostaticallyprinted ink may include an additive or a plurality of additives. Theadditive or plurality of additives may be added at any stage of theproduction of the electrostatic printing ink. The additive or pluralityof additives may be selected form a wax, a surfactant, biocides, organicsolvents, viscosity modifiers, materials for pH adjustment, sequesteringagents, preservatives, compatibility additives, emulsifiers and thelike. The wax may be an incompatible wax. As used herein, “incompatiblewax” may refer to a wax that is incompatible with the resin.Specifically the wax phase separates form the resin phase upon coolingof the resin fused mixture, after the transfer of the ink film to thelabel substrate, for example, from an intermediate transfer member,which may be a heated blanket.

Method

Described herein is a method of providing a printed label comprising:providing a label substrate having disposed thereon an electrostaticallyprinted ink; applying a UV curable overcoat composition to the printedink, wherein the UV curable overcoat composition comprises: (i) UVcurable monomers and/or oligomers; and (ii) a slip agent.

In some examples, the method of providing a printed label comprises:providing a label substrate having disposed thereon an electrostaticallyprinted ink; applying a UV curable overcoat composition to the printedink, wherein the UV curable overcoat composition comprises: (i) acomponent selected from UV curable monomers and/or oligomers; and (ii) aslip agent; curing the overcoat composition under UV irradiation with anoutput power of 2500 W or less.

In some examples, the method of providing a printed label comprises:providing a label substrate having disposed thereon an electrostaticallyprinted ink; applying a UV curable overcoat composition to the printedink, wherein the UV curable overcoat composition comprises: (i) acomponent selected from UV curable monomers and/or oligomers; and (ii) aslip agent; curing the overcoat composition under UV irradiation with anoutput intensity at the surface of the substrate, that is, an effectiveenergy at the surface (sometimes referred to as the dosage) of 40 mJ/cm²or less.

Examples of the method described herein are depicted schematically inFIGS. 1 and 2, in which the following reference numerals are used toidentify the features indicated: reference numeral “1” denotes a printedlabel; reference numeral “2” denotes a label substrate; referencenumeral “3” denotes an electrostatically printed ink or an electrostaticprinting ink; reference numeral “5” denotes a printed label substrate;reference numeral “4” denotes a UV curable overcoat composition or a UVcured overcoat composition; reference numeral “6” denotes a primer; andreference numeral “10” denotes an adhesive that may be applied (at anystage of the method) to the opposing surface of the label substrate tothe surface onto which the electrostatic printing ink is or will beapplied or may have been applied to the label substrate prior tocommencement of the method.

FIG. 1 depicts a method in which a printed label substrate (5) having anelectrostatically printed ink (3) disposed thereon is provided. A UVcurable overcoat composition (4) is applied to the printed ink (3),wherein the UV curable overcoat composition comprises (i) a componentselected from UV curable monomers and/or oligomers; and (ii) a slipagent. In some examples, the UV curable overcoat composition is thencured by using UV irradiation. In some examples, the curing of the UVcurable overcoat composition causes polymerisation of the componentselected from UV curable monomers and/or oligomers. In some examples,the curing of the UV curable overcoat composition causes thepolymerisation of the component selected from UV curable monomers and/oroligomers and a cross-linking reaction with any unreacted functionalgroups within the electrostatically printed ink.

In some examples, the UV curable overcoat composition may be applied byany suitable technique. In some examples, the UV curable overcoatcomposition is applied by gravure coating, flexo coating, screen coatingor electrostatic printing. In some examples, the UV curable overcoatcomposition may be applied by using a process in-line with theelectrostatic printing of the electrostatic printing ink.

In some examples, the method comprises applying a corona treatment tothe surface of the printed label substrate (5) before applying the UVcurable overcoat composition.

In some examples, the ultraviolet light has an output power of 5000 W orless, in some examples, 4000 W or less, in some examples, 3000 W orless, in some examples 2500 W or less, in some examples, 2000 W or less,in some examples 1500 W or less. In some examples, the ultraviolet lighthas an output power of 500 W or more, in some examples, 1000 W or more.

In some examples, the ultraviolet light has an effective energy at thesurface of 40 mJ/cm² or less. In some examples, the ultraviolet lighthas an effective energy of 1 mJ/cm² or more.

In some examples, the method comprises applying a corona treatment tothe printed label substrate before applying the UV curable overcoatcomposition.

FIG. 2 depicts a method in which a label substrate (2) is provided. Anelectrostatic printing ink (3) is electrostatically printed onto thelabel substrate (2) to form a printed label substrate (5) having anelectrostatically printed ink (3) disposed thereon. A UV curableovercoat composition (4) is then applied to the printed ink (3), whereinthe UV curable overcoat composition comprises (i) a component selectedfrom UV curable monomers and/or oligomers; and (ii) a slip agent. Insome examples, the UV curable overcoat composition is then cured byusing UV irradiation. In some examples, the curing of the UV curableovercoat composition causes polymerisation of the component selectedfrom UV curable monomers and/or oligomers. In some examples, the curingof the UV curable overcoat composition causes the polymerisation of thecomponent selected from UV curable monomers and/or oligomers and across-linking reaction with any unreacted functional groups within theelectrostatically printed ink.

In some examples, electrostatically printing an electrostatic printingink onto the label substrate may comprise printing any electrostaticprinting ink described herein by any suitable electrostatic printingprocess. In some examples, electrostatically printing an electrostaticprinting ink onto the label substrate may comprise liquidelectrostatically printing a liquid electrostatic printing ink onto thelabel substrate. In some examples, electrostatically printing anelectrostatic printing ink onto the label substrate may comprise liquidelectrostatically printing a liquid electrostatic printing ink onto thelabel substrate by using a liquid electrostatic printing apparatus.Examples of suitable liquid electrostatic printing apparatus are the HPIndigo digital presses.

FIG. 3 depicts a method in which a label substrate (2) is provided. Aprimer (6) is applied to the label substrate. An electrostatic printingink (3) is then electrostatically printed onto the label substrate (2)to form a printed label substrate (5) having an electrostaticallyprinted ink (3) disposed thereon. A UV curable overcoat composition (4)is then applied to the printed ink (3), wherein the UV curable overcoatcomposition comprises (i) a component selected from UV curable monomersand/or oligomers; and a slip agent. In some examples, the UV curableovercoat composition is then cured by using UV radiation. In someexamples, the curing of the UV curable overcoat composition causespolymerisation of the component selected from UV curable monomers and/oroligomers. In some examples, the curing of the UV curable overcoatcomposition causes the polymerisation of the component selected from UVcurable monomers and/or oligomers and a cross-linking reaction with anyunreacted functional groups within the electrostatically printed ink.

In some examples, the primer may be applied by any suitable technique.In some examples, the primer is applied by gravure coating, flexocoating, screen coating or electrostatic printing. In some examples, theprimer may be applied by using a process in-line with the electrostaticprinting of the electrostatic printing ink.

In some examples, the curing of the overcoat composition occurs when theprinted label substrate having an overcoat composition disposed on theprinted ink is transported past a UV irradiation source at a speed of100 m/min or less, in some examples, 75 m/min or less, in some examples,50 m/min or less, in some examples, 40 m/min or less, in some examples,about 30 m/min. In some examples, the curing of the overcoat compositionoccurs when the printed label substrate having an overcoat compositiondisposed on the printed ink is transported past a UV irradiation sourceat a speed of 1 m/min or more, in some examples, 10 m/min or more, insome examples, 15 m/min or more, in some examples, 20 m/min or more, insome examples, 25 m/min or more. In some examples, the curing of theovercoat composition occurs when the printed label substrate having anovercoat composition disposed on the printed ink is transported past aUV irradiation source at a speed of 1 m/min to 100 m/min, in someexamples, 10 m/min to 75 m/min, in some examples, 15 m/min to 50 m/min,in some examples, 20 m/min to 40 m/min.

EXAMPLES

The following illustrates examples of the materials, methods and relatedaspects described herein. Thus, these examples should not be consideredto restrict the present disclosure, but are merely in place to teach howto make examples of compositions of the present disclosure. As such, arepresentative number of compositions and their method of manufactureare disclosed herein.

Example 1

A label substrate comprising a primer disposed on a surface of the labelsubstrate and a liquid electrostatically printed ink was prepared byproviding a label substrate comprising polyethylene (Clear P25thickness: 80 μm; from Nirotek) which was primed with DiGiPrime 050(from Michelmann) and then liquid electrostatically printed withElectroInk 4.5 (from HP Indigo) by using an HP Indigo WE6600electrostatic printing press.

A UV curable overcoat composition comprising ACTDigi® Low Odor PackagingUV OPV RDS000617 (an acrylate-containing UV curable overcoat varnish;from Actega Coatings & Sealants) and 2.5 wt. % of Uvdry Slip Additive (aslip agent from Paragon) was applied to the printed ink and cured byusing an ABG coating system containing an anilox roller having 200lines/inch (78.7 lines/cm) using a coating speed of 25 m/min, a UV lamp(from GEW) output power of 1090 W and a corona density of 800 W. Theresulting printed label was tested for water, chemical and mechanicalresistance as described below.

Example 2—Comparative Example

A printed label was prepared as described in Example 1 except that a UVlamp output power of 2980 W was used instead of 1090 W.

Example 3—Comparative Example

A printed label was prepared as described in Example 1 except that noslip agent was added to the UV curable overcoat composition.

Water Resistance

Printed labels prepared according to Examples 1 to 3 were immersed inwater at room temperature for 1, 2, 3 and 20 hour periods. The inkcoverage of each of the labels is included in Table 1 with high coverageindicating an ink coverage of 300-360% and low coverage indicating anink coverage of 100-200%. The samples were removed from the water afterthe indicated time period and wiped before a peeling test was conducted.The peeling test was conducted by applying an adhesive tape (3M Scotchtape 810) to the overcoat layer of each of the substrates. The adhesivetape was attached to the overcoat composition of each printed label bypassing a 2 kg roller over the printed label 4 times. The adhesive tapewas then immediately peeled off and the peeling resistance wasdetermined. The peeling resistance was determined by visually inspectingthe printed label after the adhesive tape had been removed from thesample, with 0% indicating that no ink was left on the printed labelafter the peeling test and 100% indicating that no ink was removed bythe removal of the adhesive tape. The samples were also tested forpeeling resistance before immersion in water; all samples resulted in avalue of 100% before immersion in water. The results are provided inTable 1A below. It is clear from the results that the addition ofreducing the UV curing intensity significantly improves the waterresistance.

TABLE 1A Water resistance test results UV lamp output Ink 1 h 2 h 3 h 20h Example power [W] Coverage [%] [%] [%] [%] 1 1090 high 100 100 100 100low 100 100 100 100 2 (Comp.) 2890 high 0 low 0 3 (Comp.) 1090 high 100100 100 100 low 100 100 100 100

In further tests on Example 1, the effect of UV intensity on the waterresistance of the labels was tested and the results are as shown inTable 1B below.

TABLE 1B Effect of intensity on water resistance Lamp output Measuredoutput Intensity Resulting label's power [W] intensity [mJ/cm²] rangewater resistance <1500  5-15 low  80-100% 1500-2500 15-40 medium 30-70%2500-5000 40-70 high Less than 20%

UV output (as would be incident on the substrate) intensity (MJ/cm2) wasmeasured by Honle UV scanner with Tesa UV-Strips. The input lampintensity (W) setting was done in ABG coating machine.

Chemical Resistance

Printed labels prepared according to Examples 1 to 3 were immersed invarious chemical solutions.

Ethanol Resistance

Printed labels prepared according to Examples 1 and 2 were tested forethanol resistance by using a Fogra WIKAT testing device (a rub off andcarbonating test device) by applying 1 mL of ethanol. After 30 seconds,5 strokes of the Fogra WIKAT test device were used. Then 1 drop ofethanol was applied to the sample. After 1 minute, the sample wasscratched with a felt pad provided with the Fogra WIKAT test device. Thesample was then fully submerged in ethanol for 5 minutes and thenscratched with the felt pad included with the test device. The resultsshown in Table 2 below indicate the amount of ink remaining on thelabels after they were scratched, as determined visually.

Conditioner Resistance

Printed labels prepared according to Examples 1 and 2 were tested forresistance to conditioner (Nevea conditioner) by submerging the printedlabels in a water/conditioner emulsion (50:50) for 24 h at 40° C. Thelabels were then allowed to dry for 15 min before it was subjected to ascratching test, as described above. The results shown in Table 2 belowindicate the amount of ink remaining on the labels after they werescratched, as determined visually.

Sun Spray Test

Printed labels prepared according to Examples 1 and 2 were tested forresistance to sun spray (Eucerin sun spray, SPF50) by submerging theprinted labels in sun spray for 7 days at room temperature(approximately 25° C.), followed by 1 day at 40° C. The labels were thensubjected to a scratching test, as described above. The results shown inTable 2 below indicate the amount of ink remaining on the labels afterthey were scratched, as determined visually.

Baby Oil Test

Printed labels prepared according to Examples 1 and 2 were tested forresistance to baby oil (Zwistal) by submerging the printed labels inbaby oil for 7 days at room temperature (approximately 25° C.), followedby 1 day at 40° C. The labels were then subjected to a scratching test,as described above. The results shown in Table 2 below indicate theamount of ink remaining on the labels after they were scratched, asdetermined visually.

Autoclave Test

Printed labels prepared according to Examples 1 and 2 were placed in anautoclave at 120° C. and 1 bar for 50 min or at 134° C. and 2 bar for 30min. The labels were then subjected to a scratching test, as describedabove. The results shown in Table 2 below indicate the amount of inkremaining on the labels after they were scratched, as determinedvisually.

TABLE 2 Chemical resistance and autoclave test results Chemicalresistance [%] Sun Baby Autoclave [%] Example Ethanol Conditioner sprayoil 1 bar 2 bar 1 100 0 100 100 100 100 2 (Comp.) 0 0 0 0 0 0

Rub Resistance

Printed labels prepared according to Examples 1 to 3 were placed in aSutherland Rub Tester. The rub test was performed according to ASTMD5264-98. The tested samples were then inspected visually and opticaldensity measurements were performed to evaluate the amount of inkremoved from the labels. The measured optical densities are shown inTable 3 below (the average of two tests). It is clear from these resultsthat the coloured ink was not removed by the abrasion test whenoverprinted with the overcoat composition prepared according toExample 1. However, the abrasion test removed considerable coloured inkfrom the label overprinted with the overcoat composition preparedaccording to Example 3, in which no slip agent is added to the overcoatcomposition. The results of rub resistance tests for an overcoatcomposition prepared according to Example 2 are similar to the resultsfor Example 1. This effect was also observed during the visualinspection of the labels.

TABLE 3 Rub resistance test results UV lamp output Optical Density [K]Example power [W] Before After 1 1100 1.324 ± 0.03 1.33 ± 0.03 3 (Comp.)1100 1.829 ± 0.01 1.587 ± 0.01

While the methods, printed labels and related aspects have beendescribed with reference to certain examples, those skilled in the artwill appreciate that various modifications, changes, omissions, andsubstitutions can be made without departing from the spirit of thedisclosure. It is intended, therefore, that the methods, printed labelsand related aspects be limited by the scope of the following claims.Unless otherwise stated, the features of any dependent claim can becombined with the features of any of the other dependent claims, and anyother independent claim.

1. A method of providing a printed label, the method comprising:providing a printed label substrate having disposed thereon anelectrostatically printed ink; applying a UV curable overcoatcomposition to the printed ink, wherein the UV curable overcoatcomposition comprises (i) a component selected from UV curable monomersand UV curable oligomers, and (ii) a slip agent; curing the overcoatcomposition under UV irradiation with an output power of 2500 W or less.2. The method according to claim 1, wherein the UV irradiation has anoutput power of 1500 W or less.
 3. The method according to claim 1,wherein the UV irradiation has an output power of from 1000 W to 1500 W.4. The method according to claim 1, wherein the UV irradiation isapplied for 10 seconds or less.
 5. The method according to claim 1,wherein the printed label substrate comprises a synthetic polymermaterial and has disposed thereon a primer wherein the primer isdisposed between the synthetic polymer material and theelectrostatically printed ink.
 6. The method according to claim 1,wherein the slip agent comprises a slip agent selected from: (a) esters,amides, alcohols and acids of oils; (b) fluoro-containing polymers; and(c) silicon compounds.
 7. The method according to claim 1, wherein theslip agent comprises an acrylate.
 8. The method according to claim 1,wherein the slip agent comprises a silicone acrylate.
 9. The methodaccording to claim 1, wherein the slip agent comprises a compoundselected from silicone acrylate, silicone methacrylate, acrylated alkylsiloxane, methacrylated alkyl siloxane, acrylated aryl siloxane,methacrylated aryl siloxane, acrylated allyl siloxane and methacrylatedallyl siloxane.
 10. The method according to claim 1, wherein the slipagent comprises a silicone polyether acrylate.
 11. The method accordingto claim 1, wherein the UV curable monomers and UV curable oligomers areselected from a molecule comprising a plurality of epoxide groups, and amolecule comprising a plurality of alkene groups,
 12. The method ofproviding a label according to claim 11, wherein the acrylate monomersand acrylate oligomers are selected from di-, tri-, and tetra-acrylates.13. A printed label comprising: a label substrate; an electrostaticallyprinted ink disposed on the substrate; and an overcoat compositiondisposed on the printed ink that has been cured under UV irradiation;wherein the overcoat composition comprises (i) a component selected fromUV curable monomers and UV curable oligomers, and (ii) a slip agent. 14.The label according to claim 6, wherein the curing of the overcoatcomposition was performed under UV irradiation with an output power of2500 W or less.
 15. An ink and overcoat composition set comprising: aliquid electrostatic printing ink composition; and a UV curable overcoatcomposition comprising (i) a component selected from UV curable monomersand UV curable oligomers; (ii) a slip agent; and (iii) a photoinitiator.